Tyre

ABSTRACT

A mark indicating portion provided on a sidewall portion includes a reference surface provided on a surface of the sidewall portion and marks formed on the reference surface. A surface of each mark is inclined with respect to the reference surface in a direction in which a height thereof increases from one side to the other side in a tyre radial direction.

TECHNICAL FIELD

The present invention relates to a tyre having improved legibility of amark provided on a sidewall portion.

BACKGROUND ART

on a surface of at least one of the sidewall portions of the tyre, oneor more marks which are letters, symbols, and the like indicating themanufacturer name, brand name, size, and the like of the tyre areformed. And in order to improve the legibility of the marks, forexample, the marks are formed to be one step higher than the surface ofthe sidewall portion, and ridges are provided on the surfaces of themarks (for example, see Japanese Unexamined Patent ApplicationPublication No. H9-86106).

SUMMARY OF THE INVENTION

However, conventional marks have a constant height, therefore, even whena ridge is formed on the surface thereof, they have monotonousappearance and little change in contrast. Thereby, the legibility cannotbe sufficiently improved.

An object of the present invention is to provide a tyre capable ofimproving design by providing a change in the appearance of the marksand capable of improving the legibility of the marks by giving contrastbetween the surfaces of the marks and their reference surface.

In one aspect of the present invention, a tyre comprises a sidewallportion provided with a mark indicating portion having one or moremarks, wherein the mark indicating portion comprises a reference surfaceprovided on a surface of the sidewall portion and the one or more marksformed on the reference surface, and a surface of the or each mark isinclined with respect to the reference surface in a direction in which aheight thereof increases from one side to the other side in a tyreradial direction.

In another aspect of the invention, it is preferred that the surface ofthe or each mark is inclined in a direction in which the heightincreases from inside to outside in the tyre radial direction.

In another aspect of the invention, it is preferred that the markindicating portion is provided with a plurality of small protrudingportions on either the reference surface or the surface of the or eachmark.

In another aspect of the invention, it is preferred that each of thesmall protruding portions is a truncated conical protrusion having asmaller diameter on a side of an upper end thereof.

In another aspect of the invention, it is preferred that each of thetruncated conical protrusions has a maximum diameter in a range of from50 to 1000 micro meters and a protruding height in a range of from 50 to1000 micro meters, and a distance between centers of the truncatedconical protrusions adjacent to each other is in a range of from 200 to1000 micro meters.

In another aspect of the invention, it is preferred that each of thesmall protruding portions is a rib-shaped protrusion having atrapezoidal cross section with a thickness thereof decreasing toward anupper end thereof, and the rib-shaped protrusions are arranged parallelto each other or in a non-parallel manner.

In another aspect of the invention, it is preferred that each of therib-shaped protrusions has a maximum thickness in a range of from 20 to1000 micro meters and a protruding height in a range of from 200 to 500micro meters, and a distance between the rib-shaped protrusions adjacentto each other is in a range of from 10 to 800 micro meters.

In another aspect of the invention, it is preferred that the markindicating portion is provided with a base portion projecting from thesurface of the sidewall portion at a constant height, and a surface ofthe base portion forms the reference surface.

In another aspect of the invention, it is preferred that a maximumheight of the surface of the or each mark from the reference surface islarger than the height of the base portion from the surface of thesidewall portion.

The surface of the or each marks is inclined, therefore, a manner ofreflection of light is different from the reference surface (x).Thereby, it is possible that stereoscopic effect of the marks isemphasized while an increase in weight and air resistance is suppressed.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a partial perspective view of a tyre according to anembodiment of the present invention.

FIG. 2 is an enlarged partial perspective view of marks.

FIG. 3 is an enlarged cross-sectional view of one of the marks takenalong A-A line of FIG. 2.

FIG. 4A is a partial plan view showing an arrangement of smallprotruding portions formed as truncated conical protrusions.

FIG. 4B is a cross-sectional view of the truncated conical protrusions.

FIG. 5A is a partial perspective view showing an arrangement and crosssections of the small protruding portions formed as rib-shapedprotrusions.

FIG. 5B is a partial perspective view showing another arrangement andthe cross sections of the small protruding portions formed as therib-shaped protrusions.

DESCRIPTION OF THE PREFERRED EMBODIMENT

An embodiment of the present invention will now be described below indetail.

As shown in FIG. 1, a tyre 1 in this embodiment is provided with one ormore mark indicating portions 3 in at least one of sidewall portions 2.

Each of the mark indicating portions 3 is provided with a referencesurface (x) provided on a surface (2 s) of a respective one of thesidewall portions 2 and one or more marks 4 formed on the referencesurface (x). In this embodiment, each of the mark indicating portions 3is provided with a base portion 5 which projects stepwise from thesurface (2 s) of a respective one of the sidewall portions 2 at aconstant height (H5) (that is, a top surface of the base portion is notinclined with respect to the surface (2 s)) and a surface (5 s) of thebase portion 5 forms the reference surface (x).

Each of the marks 4 is a letter, a symbol, a figure, and the like forrepresenting the manufacturer name, brand name, size, and the like ofthe tyre, and in this embodiment, a case is shown in which a brand nameconsisting of a plurality of the marks 4 is formed on the referencesurface (x).

As shown in FIGS. 2 and 3, a surface (4 s) of each of the marks 4 isinclined with respect to the reference surface (x) in a direction inwhich a height (H) thereof increases from a side of one end thereof to aside of the other end thereof in a tyre radial direction. In particular,in this embodiment, the surface (4 s) is inclined in a direction inwhich the height increases from the inside to the outside in the tyreradial direction.

As just described, the surface (4 s) of each of the marks 4 is inclinedin the tyre radial direction with respect to the reference surface (x),therefore, a change is given to the appearance of the marks 4, thereby,it is possible that the design is improved. Further, it is possible thatthe manner of light reflection is made different from the referencesurface (x), and that a large difference in contrast is brought aboutbetween when viewed from the one side and when viewed from the otherside. And by a synergistic effect of these, it becomes possible that thelegibility is improved.

As shown in FIG. 3, it is preferred that a maximum height (Hmax) of thesurface (4 s) of each of the marks 4 from the reference surface (x) islarger than the height (H5) of the base portion 5 from the surface (2 s)of each of the sidewall portions 2 from a point of view of thelegibility. Note that it is preferred that a minimum height (Hmin) ofthe surface (4 s) of each of the marks 4 from the reference surface (x)is not more than the height (H5) of the base portion 5 from a point ofview of suppressing an increase in air resistance.

It is preferred that the surface (4 s) of each of the marks 4 is a flatsurface, however, it may be a curved surface extending curvedly in anarc shape in the tyre radial direction, for example.

Further, in each of the mark indicating portions 3, as shown in FIGS. 4Aand 4B, it is preferred that a surface (s) which is either the referencesurface (x) or the surface (4 s) of each of the marks 4 is provided witha plurality of small protruding portions 15 each protruding from thesurface (s). In this embodiment, a case where each of the smallprotruding portions 15 is a truncated conical protrusion 16 having asmaller diameter on a side of an upper end thereof is shown. It ispreferred that each of the truncated conical protrusions 16 has amaximum diameter (D1) in the range of from 50 to 1000 micro meters and aprotruding height (H1) from the surface (s) in the range of from 50 to1000 micro meters, and that a distance (L1) between centers of the smallprotruding portions 15 adjacent to each other is in the range of from200 to 1000 micro meters.

It is possible that the truncated conical protrusions 16 configured assuch irregularly reflect light and make the surface (s) (the referencesurface (x) or the surface (4 s) of the mark 4) look black. Thereby, itis possible that the contour shapes of the marks 4 are made clearer,therefore, it is possible that the legibility of the marks 4 is furtherimproved. As a result of research by the present inventor, when themaximum diameter (D1) and the protruding height (H1) of each of thetruncated conical protrusions 16, and the distance (L1) of the truncatedconical protrusions 16 are outside the above ranges, the surface (s)looks whitish due to the reflection of light, therefore, the contrastdifference between the marks 4 and the reference surface (x) tends to bedecreased. Note that by configuring each of the small protrudingportions 15 to have a truncated cone shape, it is possible that thereflection of light is further suppressed while the strength isincreased as compared with a cylindrical shape.

In this embodiment, a case is shown in which the truncated conicalprotrusions 16 are arranged in a grid pattern, but they may be arrangedin a staggered pattern, or may be randomly arranged as long as thedistance (L1) satisfies the above range.

FIGS. 5A and 5B show another embodiment of the small protruding portions15. In this embodiment, a case is shown where each of the smallprotruding portions 15 is a rib-shaped protrusion 17 having atrapezoidal cross section with a thickness thereof decreasing toward anupper end thereof. The rib-shaped protrusions 17 can be arrangedparallel to each other as shown in FIG. 5A, or they can be arranged soas not to be parallel to each other (non-parallel) as shown in FIG. 5B.It is preferred that each of the rib-shaped protrusions 17 has a maximumthickness (D2) in the range of from 20 to 1000 micro meters and aprotruding height (H2) in the range of from 200 to 500 micro meters, andthat a distance (L2) between the rib-shaped protrusions 17 adjacent toeach other is in the range of from 10 to 800 micro meters. Note that ina case where the rib-shaped protrusions 17 are arranged in thenon-parallel manner, it is preferred that an average value of a maximumvalue (L2max) and a minimum value (L2min) of the distance (L2) is in therange of from 10 to 800 micro meters.

As is the case with the truncated conical protrusions 16, it is possiblethat the rib-shaped protrusion 17 irregularly reflect light and make thesurface (s) (the reference surface (x) or the surface (4 s) of the mark4) look black. Thereby, it is possible that the contour shapes of themarks 4 are made clearer, therefore, it is possible that the legibilityof the marks 4 is further improved. As a result of research by thepresent inventor, when the maximum thickness (D2) and the protrudingheight (H2) of each of the rib-shaped protrusions 17, and the distance(L2) of the rib-shaped protrusions 17 are outside the above ranges, thesurface (s) looks whitish due to the reflection of light, therefore, thecontrast difference between the marks 4 and the reference surface (x)tends to be decreased. Note that, from a point of view of the contrast,it is more preferred that the rib-shaped protrusions 17 are arranged inthe non-parallel manner.

In each of the mark indicating portions 3, it is possible that the marks4 are directly formed on the surface (2 s) of a respective one of thesidewall portions 2 without having the base portion 5 formed thereon. Inthis case, the surface (2 s) of the sidewall portion 2 forms thereference surface (x). In this case, in order to distinguish the markindicating portions 3 from other portions, it is preferred that thesurface (2 s) of each of the sidewall portions 2 is provided with a riband the like having a small height and surrounding each of the markindicating portions 3.

While detailed description has been made of the tyre as especiallypreferred embodiments of the present invention, the present inventioncan be embodied in various forms without being limited to theillustrated embodiments.

WORKING EXAMPLES (EXAMPLES)

Tyres provided with the mark indicating portions on the surfaces of thesidewall portions 2 were made by way of test according to thespecifications listed in Table 1, and then the legibility of the markswas compared. The height (H5) of the base portion was the same for allof the test tyres, and the height (H) (the maximum height (Hmax) if thesurface of each of the marks was inclined) of each of the marks from thesurface (the reference surface (x)) of the base portion was the same forall of the test tyres.

In Reference 1, each of the marks had a constant height from the baseportion. In Examples 2, 4, and 5, the small protruding portions wereformed on the surfaces of the marks. In the Example 2, the smallprotruding portions were the truncated conical protrusions each havingthe maximum diameter (D1) of 320 micro meters and the protruding height(H1) of 500 micro meters, and the distance (L1) was 400 micro meters. Inthe Examples 4 and 5, the small protruding portions were the rib-shapedprotrusions each having the maximum thickness (D2) of 160 micro metersand the protruding height (H2) of 200 micro meters, and the distance(L2) was 200 micro meters.

The legibility was evaluated by a visual observation and the evaluationis indicated by an index based on the Reference 1 being 100, wherein alarger numerical value is better.

TABLE 1 <Mark indicating portion> Ref. 1 Ex. 1 Ex. 2 Ex. 3 Ex. 4 Ex. 5Base portion Present Absent Present Mark Present Surface Not inclinedInclined (in Tyre radial direction) Magnitude relation Hmax > H5 —Hmax > H5 between Maximum height (Hmax) and Height (H5) Small protrudingportion Absent Absent Truncated Absent Rib-shaped Rib-shaped conicalprotrusion protrusion protrusion (parallel) (non-parallel) Legibility100 105 110 103 130 135

As shown in Table 1, it was confirmed that the tyres as the Examplesshowed excellent legibility of the marks.

1. A tyre comprising a sidewall portion provided with a mark indicatingportion having one or more marks, wherein the mark indicating portioncomprises a reference surface provided on a surface of the sidewallportion and the one or more marks formed on the reference surface, and asurface of the or each mark is inclined with respect to the referencesurface in a direction in which a height thereof increases from one sideto the other side in a tyre radial direction.
 2. The tyre according toclaim 1, wherein the surface of the or each mark is inclined in adirection in which the height increases from inside to outside in thetyre radial direction.
 3. The tyre according to claim 1, wherein themark indicating portion is provided with a plurality of small protrudingportions on either the reference surface or the surface of the or eachmark.
 4. The tyre according to claim 3, wherein each of the smallprotruding portions is a truncated conical protrusion having a smallerdiameter on a side of an upper end thereof.
 5. The tyre according toclaim 4, wherein each of the truncated conical protrusions has a maximumdiameter in a range of from 50 to 1000 micro meters and a protrudingheight in a range of from 50 to 1000 micro meters, and a distancebetween centers of the truncated conical protrusions adjacent to eachother is in a range of from 200 to 1000 micro meters.
 6. The tyreaccording to claim 3, wherein each of the small protruding portions is arib-shaped protrusion having a trapezoidal cross section with athickness thereof decreasing toward an upper end thereof, and therib-shaped protrusions are arranged parallel to each other or in anon-parallel manner.
 7. The tyre according to claim 6, wherein each ofthe rib-shaped protrusions has a maximum thickness in a range of from 20to 1000 micro meters and a protruding height in a range of from 200 to500 micro meters, and a distance between the rib-shaped protrusionsadjacent to each other is in a range of from 10 to 800 micro meters. 8.The tyre according to claim 1, wherein the mark indicating portion isprovided with a base portion projecting from the surface of the sidewallportion at a constant height, and a surface of the base portion formsthe reference surface.
 9. The tyre according to claim 8, wherein amaximum height of the surface of the or each mark from the referencesurface is larger than the height of the base portion from the surfaceof the sidewall portion.
 10. The tyre according to claim 2, wherein themark indicating portion is provided with a plurality of small protrudingportions on either the reference surface or the surface of the or eachmark.
 11. The tyre according to claim 2, wherein the mark indicatingportion is provided with a base portion projecting from the surface ofthe sidewall portion at a constant height, and a surface of the baseportion forms the reference surface.
 12. The tyre according to claim 3,wherein the mark indicating portion is provided with a base portionprojecting from the surface of the sidewall portion at a constantheight, and a surface of the base portion forms the reference surface.13. The tyre according to claim 4, wherein the mark indicating portionis provided with a base portion projecting from the surface of thesidewall portion at a constant height, and a surface of the base portionforms the reference surface.
 14. The tyre according to claim 5, whereinthe mark indicating portion is provided with a base portion projectingfrom the surface of the sidewall portion at a constant height, and asurface of the base portion forms the reference surface.
 15. The tyreaccording to claim 6, wherein the mark indicating portion is providedwith a base portion projecting from the surface of the sidewall portionat a constant height, and a surface of the base portion forms thereference surface.
 16. The tyre according to claim 7, wherein the markindicating portion is provided with a base portion projecting from thesurface of the sidewall portion at a constant height, and a surface ofthe base portion forms the reference surface.
 17. The tyre according toclaim 4, wherein the truncated conical protrusions are arranged in agrid pattern.
 18. The tyre according to claim 4, wherein the truncatedconical protrusions are arranged in a staggered pattern.
 19. The tyreaccording to claim 5, wherein the truncated conical protrusions arearranged randomly.
 20. The tyre according to claim 7, wherein therib-shaped protrusions are arranged in the non-parallel manner, and anaverage value of a maximum value and a minimum value of the distancebetween the rib-shaped protrusions adjacent to each other is in therange of from 10 to 800 micro meters.